Off-Grid, Small-Scale Payment System

December 5, 2025 by Bryan Cockfield No comments

An effective currency needs to be widely accepted, easy to use, and stable in value. By now most of us have recognized that cryptocurrencies fail at all three things, despite lofty ideals revolving around decentralization, transparency, and trust. But that doesn’t mean that all digital currencies or payment systems are doomed to failure. [Roni] has been working on an off-grid digital payment node called Meshtbank, which works on a much smaller scale and could be a way to let a much smaller community set up a basic banking system.

The node uses Meshtastic as its backbone, letting the payment system use the same long-range low-power system that has gotten popular in recent years for enabling simple but reliable off-grid communications for a local area. With Meshtbank running on one of the nodes in the network, accounts can be created, balances reported, and digital currency exchanged using the Meshtastic messaging protocols. The ledger is also recorded, allowing transaction histories to be viewed as well.

A system like this could have great value anywhere barter-style systems exist, or could be used for community credits, festival credits, or any place that needs to track off-grid local transactions. As a thought experiment or proof of concept it shows that this is at least possible. It does have a few weaknesses though — Meshtastic isn’t as secure as modern banking might require, and the system also requires trust in an administrator. But it is one of the more unique uses we’ve seen for this communications protocol, right up there with a Meshtastic-enabled possum trap.

Biogas Production For Surprisingly Little Effort

December 4, 2025 by Jenny List 4 Comments

Probably most people know that when organic matter such as kitchen waste rots, it can produce flammable methane. As a source of free energy it’s attractive, but making a biogas plant sounds difficult, doesn’t it? Along comes [My engines] with a well-thought-out biogas plant that seems within the reach of most of us.

It’s based around a set of plastic barrels and plastic waste pipe, and he shows us the arrangement of feed pipe and residue pipe to ensure a flow through the system. The gas produced has CO2 and H2s as undesirable by-products, both of which can be removed with some surprisingly straightforward chemistry. The home-made gas holder meanwhile comes courtesy of a pair of plastic drums one inside the other.

Perhaps the greatest surprise is that the whole thing can produce a reasonable supply of gas from as little as 2 KG of organic kitchen waste daily. We can see that this is a set-up for someone with the space and also the ability to handle methane safely, but you have to admit from watching the video below, that it’s an attractive idea. Who knows, if the world faces environmental collapse, you might just need it.

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A mirrorless camera is mounted on a stand, facing downwards toward a rotating microscope stage made of wood. A pair of wires come down from the stage, and a man's hand is pointing to the stage.

Building A Microscope Without Lenses

December 4, 2025 by Aaron Beckendorf 2 Comments

It’s relatively easy to understand how optical microscopes work at low magnifications: one lens magnifies an image, the next magnifies the already-magnified image, and so on until it reaches the eye or sensor. At high magnifications, however, that model starts to fail when the feature size of the specimen nears the optical system’s diffraction limit. In a recent video, [xoreaxeax] built a simple microscope, then designed another microscope to overcome the diffraction limit without lenses or mirrors (the video is in German, but with automatic English subtitles).

The first part of the video goes over how lenses work and how they can be combined to magnify images. The first microscope was made out of camera lenses, and could resolve onion cells. The shorter the focal length of the objective lens, the stronger the magnification is, and a spherical lens gives the shortest focal length. [xoreaxeax] therefore made one by melting a bit of soda-lime glass with a torch. The picture it gave was indistinct, but highly magnified. Continue reading “Building A Microscope Without Lenses” →

Preventing A Mess With The Weller WDC Solder Containment Pocket

December 4, 2025 by Maya Posch 13 Comments

Have you ever tipped all the stray bits of solder out of your tip cleaner by mistake? [MisterHW] is here with a bit of paraffin wax to save the day.

Hand soldering can be a messy business, especially when you wipe the soldering iron tip on those common brass wool bundles that have largely come to replace moist sponges. The Weller Dry Cleaner (WDC) is one of such holders for brass wool, but the large tray in front of the opening with the brass wool has confused many as to its exact purposes. In short, it’s there so that you can slap the iron against the side to flick contaminants and excess solder off the tip.

Along with catching some of the bits of mostly solder that fly off during cleaning in the brass wool section, quite a lot of debris can be collected this way. Yet as many can attest to, it’s quite easy to flip over brass wool holders and have these bits go flying everywhere.

That’s where [MisterHW]’s pit of particulate holding comes into play, using folded sheet metal and some wax (e.g. paraffin) to create a trap that serves to catch any debris that enters it and smother it in the wax. To reset the trap, simply heat it up with e.g. the iron and you’ll regain a nice fresh surface to capture the next batch of crud.

As the wax is cold when in use, even if you were to tip the holder over, it should not go careening all over your ESD-safe work surface and any parts on it, and the wax can be filtered if needed to remove the particulates. When using leaded solder alloys, this setup also helps to prevent lead-contamination of the area and generally eases clean-up as bumping or tipping a soldering iron stand no longer means weeks, months or years of accumulations scooting off everywhere.

Build A Pocket-Sized Wi-Fi Analyzer

December 4, 2025 by Lewin Day 7 Comments

Wi-Fi! It’s everywhere, and yet you can’t really see it, by virtue of the technology relying on the transmission of electromagnetic waves outside the visual spectrum. Never mind, though, because you can always build yourself a Wi-Fi analyzer to get some insight into your radio surroundings, as demonstrated by [moononournation].

The core of the build is the ESP32-C5. The popular microcontroller is well-equipped for this task with its onboard dual-band Wi-Fi hardware, even if the stock antenna on most devboards is a little underwhelming. [moononournation] has paired this with a small rectangular LCD screen running the ILI9341 controller. The graphical interface is drawn with the aid of the Arduino_GFX library. It shows a graph of access points detected in the immediate area, as well as which channels they’re using and their apparent signal strength.

If you’re just trying to get a basic read on the Wi-Fi environment in a given locale, a tool like this can prove pretty useful. If your desires are more advanced, you might leap up to tinkering in the world of software defined radio. Video after the break.

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Raising A GM EV1 From The Dead

December 4, 2025 by Jenny List 13 Comments

Probably the biggest story in the world of old cars over the past couple of weeks has been the surfacing of a GM EV1 electric car for sale from an auto salvage yard. This was the famous electric car produced in small numbers by the automaker in the 1990s, then only made available for lease before being recalled. The vast majority were controversially crushed with a few units being donated to museums and universities in a non-functional state.

Finding an old car isn’t really a Hackaday story in itself, but now it’s landed in [The Questionable Garage]. It’s being subjected to a teardown as a prelude to its restoration, offering a unique opportunity to look at the state of the art in 1990s electric automotive technology.

The special thing about this car is that by a murky chain of events it ended up as an abandoned vehicle. GM’s legal net covers the rest of the surviving cars, but buying this car as an abandoned vehicle gives the owner legal title over it and frees him from their restrictions. The video is long, but well worth a watch as we see pieces of automotive tech never before shown in public. As we understand it the intention is to bring it to life using parts from GM’s contemporary S10 electric pickup truck — itself a rare vehicle — so we learn quite a bit about those machines too.

Along the way they find an EV1 charger hiding among a stock of pickup chargers, take us through the vehicle electronics, and find some galvanic corrosion in the car’s structure due to water ingress. The windscreen has a huge hole, which they cover with a plastic wrap in order to 3D scan so they can create a replacement.

This car will undoubtedly become a star of the automotive show circuit due to its unique status, so there will be plenty of chances to look at it from the outside in future. Seeing it this close up in parts though is as unique an opportunity as the car itself. We’ve certainly seen far more crusty conventional cars restored to the road, but without the challenge of zero parts availability and no donor cars. Keep an eye out as they bring it closer to the road.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Pretty Protoypes

December 4, 2025 by Kristina Panos 2 Comments

Some like it flat, and there’s nothing wrong with that. What you are looking at is the first prototype of Atlas by [AsicResistor], which is still a work in progress. [AsicResistor] found the Totem to be a bit cramped, so naturally, it was time to design a keyboard from the ground up.

The case is wood, if that’s not immediately obvious. This fact is easily detectable in the lovely render, but I didn’t want to show you that here.

This travel-friendly keyboard has 34 keys and dual trackpoints, one on each half. If the nubbin isn’t your thing, there’s an optional, oversized trackball, which I would totally opt for. But I would need an 8-ball instead, simply because that’s my number.

A build video is coming at some point, so watch the GitHub, I suppose, or haunt r/ergomechkeyboards.

Flat as it may be, I would totally at least give this keyboard a fair chance. There’s just something about those keycaps, for starters. (Isn’t it always the keycaps with me?) For another, I dig the pinky stagger. I’m not sure that two on each side is nearly enough thumb keys for me, however.

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